The calorie counters are the machines are wildly inaccurate. See the sticky "Are The Calorie Counters On Cardio Machines Accurate?
It's all about your heart rate--if you get your heart rate up to the same level on both machines and maintain that rate for the same length of time, you're burning the same calories on both. Jonsgurl0531 is referring to a polar heart rate monitor with a chest strap, but you don't really need that to monitor your heart rate. You can actually do it quite effectively using the perceived exertion scale
. If it feels like you are getting to the same level on this scale on both machines and maintaining that for the same length of time, then you're burning about the same number of calories on both. If one machine feels significantly easier to you than the other, you're burning fewer calories on the easier machine.
I love the TM, but running is very hard on your whole body. The elliptical is a good alternative because it gives all your joints and your back a break. Spinning is another great alternative.
Photochick is right that the problem with numbness in your toes on the elliptical is often a posture problem. You want your feet to flat on the foot platforms, not up on your toes. You also want to be standing up straight, not leaning forward. If it's possible to check your posture in a mirror, try to do that because it often feels like you are standing up straight even when you are leaning forward slightly. You almost want to feel like you are leaning just ever-so-slightly backwards. Since the arms don't move on your elliptical, try not to grip the handrails tightly, just rest your hands on them very lightly. If you can, try to not hold onto the hand rails--this will help with your posture and it's a better workout.